Printer-compatible, pre-embossed films

ABSTRACT

Decorative films, useful for making a wide range of decorative laminates, that have a relatively deep texture on one major face and a relatively smoother, print receptive surface on the other major face. Notwithstanding the deep texture, the films have superb tracking characteristics and are compatible with a wide variety of automated printing operations. This allows automated printing equipment to print information directly onto the films.

PRIORITY CLAIM

The present patent application claims priority to U.S. ProvisionalPatent Application having Ser. No. 60/959,114, filed on Jul. 11, 2007,by Guillot et al., and titled PRINTER-COMPATIBLE, PRE-EMBOSSED FILMS,wherein said provisional application is incorporated herein by referencein its entirety.

FIELD OF THE INVENTION

The present invention relates to laminates, particularly decorativelaminates incorporating a film laminated to a substrate, wherein thefilm has a first, textured face and a second, relatively smooth faceonto which decorative information may be applied such as by printing.More particularly, the texture applied to the first face is selected sothat the film remains amenable to printing even when the texture isrelatively deep.

BACKGROUND OF THE INVENTION

Decorative laminates are widely used in the cabinet, molding, furniture,consumer electronics, paneling, boating, recreational vehicles, andother industries. One conventional decorative laminate structure isformed from an at least partially transparent decorative film that islaminated to a desired substrate. The decorative film often includesdecorative information such as the image(s) of wood grain, stone,leather, textile, fanciful designs, one or more colors in a pattern orotherwise, a human, an animal, nature, architecture, and the like. Thefilm often is made from ingredients including one or more polymers. Thedecorative information often is on the inside face of the film while theoutside face of the film bears a texture to help provide low gloss, amatted appearance, scratch and mar resistance, and/or anti-blockingresistance in printed roll, stack or other form in which a film facecontacts an adjacent film face of the same or a different film. One ormore additional layers may be incorporated into such a decorativelaminate, either between the film and the substrate or otherwise, suchas an additional decorative film, an underlay, an overlay, an adhesive,protective coating, and/or the like.

The decorative information is desirably applied onto the film usingprinting techniques such as ink jet printing, laser printing, gravureprinting, offset printing, anastatic printing, silk screen printing,transfer printing, lithographic, flexographic, other printing methods,combinations of these, and the like. Typically, the film is textured onone major face, while the decorative information is printed onto theother major face. If the film is textured prior to printing, the film isconsidered to be pre-embossed. If the film is textured after printing,the film is considered to be post-embossed.

Relatively deep textures, e.g., those textures having an Ra surfaceroughness of over about 100 microinches, preferably over 120microinches, and even over 150 microinches, are desirable in manyapplications as these tend to provide much better blocking resistanceand scratch and mar resistance than lighter textures. Also, deepertextures provide very desirable visual and tactile properties.

However, there are significant challenges involved in preparing filmshaving decorative, printed information on one face and deep texture onthe other face. It is quite difficult to print decorative informationonto the smoother side of a pre-embossed film bearing a deeper textureon the other side. Due to the deeper texture, such films tend toexperience chatter or other tracking problems when transported through aprinter. Chatter generally refers to an undesired, vibration of themoving film, especially side-to-side, repeated movement or jitter of afilm. These problems can seriously compromise the quality of the printedinformation. Quite simply, many embodiments of conventional pre-embossedfilms with deep texture have not been as printer-compatible as might bedesired. There is a bias in the decorative laminate industry,particularly under the relatively stringent commercial standardsapplicable to the decor printing industry, against trying to print ontosuch deeply embossed films.

The industry generally prefers to post-emboss printed films. In thistechnique, the film can be relatively smooth on both sides at the timeof printing and have good tracking characteristics through the printer.The film is then embossed after printing.

Post-embossing involves some drawbacks, though. First, it involves anentire extra stage of manufacture that requires expensive equipment,facility space, utilities, and other resources, all of which addconsiderable expense to the manufacturing process. Also, post-embossingcan be a bottleneck in the overall manufacturing line, adverselyimpacting throughput. The printed information is also put at risk, asextra handling is required for the film to traverse through thepost-embossing stage of manufacturing. If the printed information isdamaged or otherwise compromised during the embossing stage, scrap isproduced and yields go down. Additionally, post-embossed texture is lesspermanent than pre-embossed texture. Under pressure and heat, which aretypically used to form decorative laminates, a significant portion ofpost-embossed texture can be lost. Thus, a post-embossed film may haveto be over-textured to meet a texture specification applicable to thelaminated product. It is hard to control the uniformity of the embossingon the final product in this kind of scenario. There can be considerablevariation, and specifications have to be less stringent to accommodatethis.

Another technical solution is to use pre-embossed films that have a verylimited degree of texture, e.g., an Ra surface roughness of under 90microinches, even under 80 microinches, or even under 70 microinches. Bylimiting the texture on the “embossed” surface of a film, thepre-embossed film may exhibit acceptable tracking properties duringprinting. However, such light texture does not provide acceptablescratch and mar resistance and/or anti-blocking protection in manyapplications. Films bearing such light texture may also exhibit glosslevels that are higher than desired. Additionally, the visual andtactile sensations offered by these films may tend to be unappealing toconsumers, particularly when the decorative information corresponds tonatural surfaces such as wood grain, stone, leather, fabrics, and thelike.

Another technical solution is to print the decorative information onto aseparate film that is sufficiently smooth on both sides to be bothprinter compatible and ink receptive and then to incorporate thisprinted film into a decorative laminate that includes a separate, moredeeply textured film as an overlay. This involves adding a whole extracomponent in the product and is accompanied by the associated extrastages of manufacture and resources to handle.

The industry could benefit significantly from a printer-compatible,pre-embossed film having a deeper texture.

SUMMARY OF THE INVENTION

The present invention provides decorative laminate films that have arelatively deep texture on one major face and a relatively smoother,print receptive surface on the other major face. The films are usefulfor making a wide range of decorative laminate products. Notwithstandingthe deep texture, the films have superb tracking characteristics and arecompatible with a wide variety of automated printing operations. Thisallows automated printing equipment to print information directly ontothe films rather than onto separate sheets which then are laminated to adeeply textured sheet as has been practiced conventionally in the past.(Certain embodiments may incorporate separately printed layers where acombination of overlapping printed layers helps to achieve one or morekinds of desired visual effects.) The ability to print onto an alreadydeeply textured sheet completely eliminates any need to post-emboss thefilm after printing, saving considerable time, expense, and facilityresources.

As used herein, a deep texture is a texture having an Ra surfaceroughness of at least 100 micrometers, preferably over 120 micrometers,and more preferably over 150 micrometers. A procedure for determining Rasurface roughness is provided in the Detailed Description, below.

Advantageously, the film can be textured with an embossing tool (whichin some modes of practice is a textured roller) having a unique texturewhich, in the present context, is able to perform many differentfunctions. The texture can be relatively deep and yet the texture has aconfiguration such that the film nonetheless has good trackingcharacteristics to be printed at the resolutions demanded in thedecorative laminate industry. The texture on the tool has contours thatallow the texture to be formed repeatedly and consistently on movingfilms at high speed with exceptional uniformity along the length of afilm. This extremely uniform quality is a significant quality controlasset. The texture also provides excellent scratch and mar resistanceand anti-blocking protection. The texture is also extremely stable underheat and pressure so that there is much less need, and even no need insome embodiments, to overtexture the films to achieve a desired degreeof final texture remaining after lamination. The ability to use a moretargeted degree of texture with less overtexturing further contributesto enhanced printer compatibility, inasmuch as overtexturingconventionally would be expected to contribute to tracking problems andpoor or unacceptable print quality.

In one aspect, the present invention relates to a method of making atextured, decorative laminate film. A molten film is extruded. While theextruded film is at least partially molten, the film passes through agap between first and second tooling surfaces and contacts said firstand second tooling surfaces that are maintained at one or moretemperatures below the melt temperature of the molten film in a mannereffective to help cause the molten film to set and solidify as the filmpasses through the gap. The first tooling surface includes a pluralityof irregular and random depressions that provide cavities that are atleast partially filled by the molten film as the film passes over thefirst tooling surface and sets. The second tooling surface is relativelysmoother than the first major surface. A solidified film is formed thatincludes a first, textured major face having an Ra surface roughness ofgreater than about 100 microinches and a second, print receptive majorface having an Ra surface roughness of less than 100 microinches,wherein the ratio of the Ra surface roughness of the first major face ofthe film to the Ra surface roughness of the second major face of thefilm is in the range from about 1.1:1 to about 500:1. Decorativeinformation is printed onto the second major face of the film.

In another aspect, the present invention relates to a decorativelaminate film. The film includes a first major face having a random andirregular pattern of protuberances having different shapes and sizes,said first major surface having an Ra surface roughness of at least 100microinches. The film also includes a second, print receptive majorface, wherein the ratio of the Ra surface roughness of the first majorface of the film to the Ra surface roughness of the second major face ofthe film is in the range from about 1.1:1 to about 500:1. The film alsoincludes decorative information printed onto the second major face.

In another aspect, the present invention relates to a decorativelaminate that includes a substrate and a decorative laminate film bondeddirectly or indirectly to the substrate. The decorative laminate filmincludes a first major face and a second, print receptive major face.The first major face includes a random and irregular pattern ofprotuberances having different shapes and sizes, said first majorsurface having an Ra surface roughness of at least 100 microinches. Theratio of the Ra surface roughness of the first major face of the film tothe Ra surface roughness of the second major face of the film is in therange from about 1.1:1 to about 500:1. Decorative information is printedonto the second major face.

In another aspect, the present invention relates to a method of making adecorative laminate film that includes the steps of extruding a filmhaving first and second major surfaces. A random, irregular, anddirectional texture is formed on the first major surface while the filmis at least partially molten. After forming said texture on the firstmajor surface, printing decorative information onto the second majorsurface of the film. Optionally, after printing, the film is laminateddirectly or indirectly onto a substrate.

In another aspect, the present invention relates to a method of making adecorative laminate. A decorative laminate film is prepared according toany method described herein. The film is then directly or indirectlybonded the film to a substrate.

In another aspect, the present invention relates to a method of making adecorative laminate. Any decorative laminate film as described herein isprovided. This film is then directly or indirectly to a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates one system in which a printable,textured film may be prepared using extrusion techniques.

FIG. 2 schematically illustrates a portion of the system of FIG. 1,showing the path of the extruded film through a set of rollers in whichone side of the film is textured and the film is set.

FIG. 3 is a copy of a pair of photographs showing the texture on thepre-embossed side of the film and the print side of the film,respectively, taken at a magnification of 700%.

DETAILED DESCRIPTION

The embodiments of the present invention described below are notintended to be exhaustive or to limit the invention to the precise formsdisclosed in the following detailed description. Rather the embodimentsare chosen and described so that others skilled in the art mayappreciate and understand the principles and practices of the presentinvention.

FIGS. 1 and 2 schematically illustrate one way in which a printable,textured film 12 may be prepared. As seen best in FIG. 1 and as anoverview, system 10 includes as main components extruder 14, heatexchanger 34, texturing station 36, viewing station 44, automaticprofile controller 46, slitter 54, and winder 56. The path of film 12through system 10 from the extruder 14 to the winder 56 is shownschematically by the dotted line representing film 12. Various rollers58 help guide and tension the film 12 during transport through thesystem 10. Decorative information may be printed onto the film to formdecorative sheets, and these decorative sheets may then be incorporatedinto decorative laminate structures.

In more detail, extruder 14 includes hopper 16 into which one or moresupplies of feed material(s) schematically shown as 18, are loaded intoextruder 14 to form the film 12. The principles of the present inventionare extremely versatile and can be beneficially used with a wide rangeof extrudable compositions. That the present invention is so flexible interms of material choices provides a significant commercial advantage.In representative embodiments, the feed material includes one or morethermoplastic polymers selected from free radically polymerized polymers(such as poly(meth)acrylates, polystyrenic polymers, polyolefins, and/orothers derived from ingredients comprising free radically polymerizedmonomers having carbon-carbon double bonds), polyester, polyurethane,polycarbonate, polyacetal, polyether, polyamide, polyimide, polyurea,combinations of these, and the like. Polyvinyl chloride (PVC) is aspecific example of one suitable polymer for forming very durabledecorative laminate sheets and corresponding decorative laminates of thepresent invention.

In some modes of practice, thermosetting polymer(s) may be used if thethermosetting reaction can be delayed until after the texture is formedin the film 12, as desired texture characteristics could be compromisedif thermosetting were to proceed too far before texturizing occurs. Forinstance, if a polymer having radiation curable functionality (e.g.,functionality curable upon exposure to a suitable energy source such asultraviolet energy or electron beam energy) were to have a suitable melttemperature so that extrusion could occur with undue risk of triggeringtoo much crosslinking prior to texturizing, thermosetting polymer(s) maybe used as at least a portion of the feed 18 supplied to hopper 16. Asuitable curing station (not shown) could then be incorporated intosystem 10 to cure film 12 downstream from the texturing station 36.

In addition to one or more polymers, the feed 18 introduced into hopper16 may optionally include one or more other, optional ingredients suchas one or more plasticizers, ultraviolet stabilizers, antioxidants,flatting agents; waxes; dispersants; inorganic particles; pigments;fungicides, bactericides, antistatic agents, fire retardants,combinations of these, and the like. In preferred embodiments,particularly those including PVC, the feed 18 includes less than 5 partsby weight, preferably less than 2 parts by weight, more preferably lessthan 0.5 parts by weight, and even less than 0.1 parts by weight ofplasticizer per 100 parts by weight of the feed. It has been found thatrestricting, and more desirably avoiding, plasticizer provides rigidfilm characteristics, improved embossing retention, enhanced wearcharacteristics, reduced plasticizer or other component migration,enhanced flame retardance, superior film lay flat, and/or improved stainresistance. A particularly preferred feed 18 includes no plasticizer.

From hopper 16, the feed 18 is fed into the barrel (not shown) of theextruder, which is housed in barrel section 20. Housing shrouds 22enclose the barrel to help isolate the barrel from the ambientsurrounding the extruder. The barrel section 20 and hopper 16 aremounted on support structures 24 and 26.

Extruder die station 28 includes the die through which the molten feedis extruded as film 12. Extruder die station 28 is supported upon dolly30 for mobility. The die is heated to help ensure that the exudateleaves die station 28 in a fully molten state at an appropriatetemperature. Adapter 32 couples the extruder barrel to the die station28.

In representative embodiments, film 12 extruded from the die may have awidth in the range from a few inches to many tens of inches. Aconvenient film width suitable for commercial scale production would bein the range from about 8 inches to 120 inches. For film this wide, thethermal mass of the die is rather large. Accordingly, it is desirable ifheat energy can be added at multiple locations throughout the die tofacilitate temperature control. By way of example, one die configured toextrude film having a width in the range from about 60 inches to about70 inches has seven heat input locations spaced generally equally acrossthe face of the die. Electric heating is convenient for this purpose.

The temperature of the extruder 14 and die can depend upon factorsincluding the nature of the feed 18. Generally, it is desirable to heatthe feed 18 sufficiently so that it is fully molten when it leaves theextruder 14 as an exudate. However, the temperature should not be sohigh that there is an undue risk of thermally damaging the feed 18. Italso is convenient to use a temperature gradient in which thetemperature is ramped up to the final desired temperature. By way ofillustration, when extruding a PVC polymer having a melt temperature ofabout 380° F. through extruder 14 having five heating zones and a heateddie, the first (closest to the hopper 16) through fifth (closest to thedie station 28) extruder zones may be set at 312° F., 320° F., 330° F.,340° F., and 350° F., respectively, while the die conveniently has atemperature set point of 355 F, although the die temperature mayindependently vary across the various die heating locations to helpcontrol the film thickness as described further below. Even though theseset temperatures are below the melt temperature of the PVC polymer, thesignificant shear energy from the extruder screw adds enough heat energyto melt the polymer.

The molten film 12 is then processed in the texturing station 36 to setthe film, forming the textured and printable surfaces. To ensure goodtransfer of the molten feed 18 from the die to the texturing station 36,it is desirable to place the texturing station 36 as close as ispractically feasible to the die. A distance of about 2 inches to about12 inches between the die outlet to the gap 45 (see FIG. 2) between thetop roller 38 and the middle roller 40 has been found to be suitable.

The texturing station 36 generally includes a tool having a surface usedfor imparting the desired texture onto the film 12 and optionally one ormore other components to help with film formation, transport, or thelike. For purposes of illustration, station 36 includes top roller 38,middle roller 40, and bottom roller 42 mounted within a supportingstructure schematically designated by the enclosure 47. The top roller38 and middle roller 40 contribute to forming the textured and printablefaces of film 12, while bottom roller 42 helps to avoid chatter andprovide a smooth release as film 12 leaves texturing station 36. Lineoperators or other observers may view the activities within texturingstation 36 from the viewing station 44, which conveniently may be in theform of a catwalk.

The middle roller 40 is textured for embossing the film 12 and includesat least one primary and at least one additional secondary texture. Inone embodiment, the surface of the middle roller 40 is chrome. The atleast one primary texture generally includes a plurality of depressionsformed in the roller surface. When the molten film material flows overthe surface of middle roller 40, the molten material fills and/orpartially fills these depressions and sets. In essence then, thesedepressions act like female molds for forming correspondingprotuberances on the adjacent (proximal) major surface of the film 12.

The depressions formed in middle roller 40 generally are irregular andrandom. Irregular refers to the shape and dimensions of the depressions,while random refers to the arrangement of the depressions on the rollersurface. Using a population of irregular depressions randomly formed onthe surface of middle roller 40 contributes to the advantages describedherein, especially tracking performance, scratch and mar resistance, andblocking resistance and still maintain an acceptable print quality orgraphic reproduction.

Irregular means that the depressions include a population of depressionsincluding a plurality of shapes and a plurality of sizes. Viewed fromthe top, representative embodiments of the depressions can be circularin a range of sizes and/or oblong in a range of sizes and acicularity(ranging from close to circular to string-like). The aciculardepressions preferably meander in a nonlinear fashion and/or may includeone or more branches. Branches may extend outward from one portion of adepression and rejoin the depression at another portion. The depressionspreferably have rounded contours to facilitate smooth, easy release ofthe set film 12 from middle roller 40, although the bottoms of thedepressions may be flat for machining convenience.

The depressions will also vary in terms of their lengths, widths, anddepths both among features and optionally intrafeature as well. Thedimensions of these depression features can vary over a wide rangedepending upon factors including the film thickness, the desired enduse, the nature of the printing equipment to be used, and the like.Generally, if the depressions are too small, the resulting texture onfilm 12 may be too fine to provide the desired scratch and marresistance and/or blocking resistance. A texture that is too fine mayimpair visual and texture effects desired in the resultant decorativelaminate product. On the other hand, if the texture is too much, moretexture telegraphing from one side of the film to the other than isdesired may occur, mechanical properties of the film may be reduced toomuch, tracking through printing devices may suffer, and/or unacceptableprint quality may be incurred.

Balancing such concerns, one representative but non-limiting set ofroller depressions may have dimensions effective to provide an embossedfilm surface having an Ra surface texture as specified herein. This maycorrespond to depressions having a range of depths up to about 5thousandths to 6 thousandths of an inch, which in turn may be platedwith a surface covering, e.g., chrome having a thickness of 2 mils orless, even 1 mil or less. Suitable widths and lengths of the depressionsmay vary over a very wide range, particularly given that preferredroller textures include a population of depressions having string-likecontours of varying lengths and widths. FIG. 3 and the correspondingdiscussion below shows preferred embodiments of representative filmtextures that would result from correspondingly textured middle roller40. For instance, the protuberances formed on the pre-embossed side 105of the film 100 shown in FIG. 3 would be formed by a roller havingcorresponding depressions in its surface that contacted and embossed thefilm 100.

Random means that the depressions formed on the roller surface are notarranged in regular columns or rows. So long as the features arestaggered so as not to be arranged in regular columns or rows, thetexture can be directional, e.g., uni-directional, bi-directional,multi-directional, or the like. For instance, the textures shown in FIG.3 are directional and yet staggered so as to be random. On thecorresponding roller used to form such protuberances in the film 12, theroller depressions would be directionally oriented generallycircumferentially around the roller surface, generally perpendicular tothe roller axis, so that the resultant protuberances formed on film 12are generally directionally aligned with the direction of the movingfilm 12 as the film 12 moves over the roller surface.

The density of the depression features on the surface of middle roller40 may vary over a wide range. For instance, depressions may be formedso that individual depressions generally are isolated from otherdepressions by intervening land areas, analogous to the dimpled surfaceof a golf ball. Alternatively, depressions may be formed so that thepopulation of depressions may include two or more depressions thatoverlap at least partially in a depression cluster with an interveningland area between this cluster and another cluster and/or depression. Instill other embodiments, depressions may be formed in such a densitysuch that substantially the entire surface of the middle roller 40 iscovered by overlapping depressions with very little unsurfaced land arearemaining. The texture desirably covers at least 50% of the rollersurface, preferably at least 80% of the surface, more preferably atleast 98% or more of the surface.

The texture on middle roller 40 can be formed in a variety of ways,including via acid-etching, electromechanical milling, laser engraving,die milling, peening, and/or other suitable methods. In onecircumstance, such as when a tool according to a die mill method is usedto form the texture on middle roller 40, the tool may have to berepeatedly run back and forth over the surface in order to complete thetexture. In this sense, each pass could be said to repeat the pattern onthe tool. Yet, if the pattern on the tool is irregular or random and/orif the tool is run over the roller in different directions and/orconfigurations, or in a spiraling or other nonparallel path, the textureon the roller will be deemed to be random and irregular in the practiceof the present invention.

Advantageously, the primary texture used on middle roller 40simultaneously serves multiple functions in the context of the presentinvention. First, the texture on middle roller 40 allows acorresponding, relatively deep texture to be formed on the proximalmajor face of film 12 with minimal telegraphing of this texture onto theother, print receptive major face of film 12 even when film 12 is movingover middle roller 40 at relatively high line speeds suitable forcommercial scale production. In short, the roller texture is animportant factor that allows one major face of the film 12 to betextured while the other major face of film 12 remains relatively smoothand printable. Without wishing to be bound by theory, it is believedthat the use of depressions to form a substantial portion of the primarytexture features of middle roller 40 allow this. These depressions allowthe molten material used to form film 12 to flow smoothly over and fillthe depressions as the molten material sets. The other major face of thefilm is far less affected by this smooth filling action than might beexpected. In contrast, if the roller surface were to include an undueamount of protuberances, these could cause enough turbulence or otherflow disruption such that substantial telegraphing of texture to theother major surface of the film could occur. If this were to happen,print receptive qualities of the other major surface could becompromised.

Additionally, the texture characteristics of middle roller 40 yielddeeply textured films 12 that nonetheless track consistently wellthrough printing devices at line speeds suitable for commercial scaleproduction. This is counter to conventional wisdom in the industry,where deeply textured films experience tracking and chatter problemsduring attempted printing operations. Without wishing to be bound bytheory, it is believed that the resultant texture formed on film 12,which is essentially randomly and uniformly distributed over one majorsurface of film 12 allows very effective and uniform air bleedcharacteristics under the film 12 as it traverses through a printer. Asa consequence, localized pressure changes under the film 12 having amagnitude sufficient to induce tracking issues are substantiallyavoided.

Pre-embossed texture also avoids exposing print quality and designclarity on the printed sheets to post-emboss damage risk.Post-embossing, even when intended to be mainly applied to one majorface of a film can nonetheless result in telegraphing of the embossedtexture to the opposite, printed face. Print quality can be lost to somedegree if this were to happen in post-embossing processes. Thus, printquality and design clarity of as printed decorative information tend tobe retained to a higher degree on pre-embossed films than onpost-embossed films.

Further, the molten material is able to smoothly, consistently, andsubstantially fully and/or partially fill the depressions on the rollerbefore the film 12 sets. This means that the resultant texture is veryconsistent along the full length of a roll and from roll-to-roll, dayafter day. This is an important advantage in commercial scale productionthat greatly eases quality control activities. This extreme consistencyis much more difficult to achieve on a roller that includes relativelygreater proportions of protuberances versus depressions, particularlywhen the protuberances are closely spaced sufficiently to unduly disruptflow over the roller surface. Thus, although middle roller 40 mayinclude some amount of protuberances in addition to depressions, it isdesirable to minimize these protuberances so that they constitute lessthan 20%, more preferably less than 10%, and more preferably less than2% of the surface area of middle roller 40.

Another advantage is that the resultant texture formed on the decorativesheet provides the sheet and a laminate incorporating the sheet withsuperb scratch and mar resistance and anti-blocking protection. Inpractical effect, the texture as formed on the embossed surface of thefilm includes a plurality of protuberances projected generally upwardfrom the film surface. For anti-blocking protection, these act likestand-offs, reducing the contact area with an adjacent film face whenstacked, wound on a roll, etc.

Another advantage is that embossing the extruded film 12 at the time thefilm is first set after emerging from the extruder 14, i.e.,pre-embossing the film, completely eliminates any need to post-embossthe film 12 which typically has occurred after printing. Since anextruded film desirably is run between a pair of rollers to set it at auniform thickness, allowing one of these setting rollers to be thetextured middle roller 40 eliminates the entire post-embossingmanufacturing stage, leading to substantial cost savings in manufacture.This also helps to protect the information printed on the film 12, whichis at risk of being damaged if the film bearing the printing must be runthrough post-emboss equipment. Yield losses due to emboss process issuesor to printing damage occurring during a post-emboss are entirelyavoided. Since the post-emboss stage can sometimes be a bottleneck inthe manufacture process, eliminating the post-emboss also dramaticallyincreases throughput. Further, the facility floor space previously takenup by post-emboss equipment can now be used by other productive stages,increasing throughput even more.

Still another advantage is that the pre-embossed texture of the presentinvention is much more stable under heat and pressure than a post-embosstexture. For instance, when a post-embossed sheet is laminated onto asubstrate under heat and pressure, a significant portion of the textureis lost, e.g., 30% or even more. This has provided a motivation toover-texture post-embossed films to ensure that the laminated productstill bears enough texture after the lamination stage. Sinceover-texturing makes printing more difficult, if not impractical,printing typically occurred prior to post-embossing. In contrast, apre-embossed film laminated under otherwise identical conditions losessubstantially less texture, e.g., 11% or even less. Indeed, in PVC filmembodiments incorporating no plasticizer, the surface roughness of thefilms following lamination was the same as the decorative sheet prior tolamination within the measurement capabilities of the measurementinstrument. In other words, within the measurement capabilities of theinstrument, no loss of texture after lamination could be identified.

Thus, pre-embossed sheets of the present invention can be fabricatedwith a texture that is much closer to the final, desired texture goal.Alternatively stated, there is much less need to resort to significantovertexturing protection when practicing the present invention. Thismore targeted texture in combination with the right kind of texture isan important combination that allows the film 12 to be printercompatible, as much as overtexturing would tend to be associated with asignificant risk of printer incompatibility.

It is also believed that many advantages would be realized in the courseof laminating these films onto substrates. Because of the stability ofthe texture under heat pressure, lamination would be able to occur undera wider range of manufacturing conditions. For instance, greater heatand/or pressure may be used in order to laminate faster, leading tohigher throughput. Due to the excellent scratch and mar resistance andblocking resistance, the films would be more compatible with a widerrange of equipment. It is also believed that the degree, nature, andpermanence of the texture will allow the visual impact of gel spots(which are believed to result from higher molecular weight lumps ofresin in the extruded film) to be hidden to a greater degree and, thus,lessened.

In addition to the primary texture described above, the middle roller 40may also incorporate one or more additional kinds of textures. Forinstance, it may be desirable to further incorporate a gloss modifying,secondary texture onto at least the film surface bearing the primarytexture. According to one convenient approach, this texture is obtainedthrough appropriate surface roughening of a plating, e.g., chromeplating, covering the primary texture. The degree of roughness can becontrolled by the grit finish used to surface the plating. Thisadditional gloss modifying texture is at a much smaller scale than thetexture provided by the depressions of the middle roller 40. By way ofanalogy, if the roller land surface(s) and depressions are viewed asplateaus and valleys respectively, the secondary texture may be viewedas shrubbery growing on the surfaces of those plateaus and valleys.Thus, returning from the analogy to the context of the presentinvention, the finer texture is provided on both the land(s) and thedepressions. The amount of this kind of texture used can vary over awide range and depends, to a large degree, upon what kind of glosscharacteristics are desired for the final product.

In embodiments of the invention in which film 12 is transparent,imparting this texture onto one major face of the film impacts the glosson the other major face even when that other major face was notphysically modified. For instance, film embodiments of the invention hadglosses on their embossed sides of about 51 on average and about 23 onaverage on the print side after moderate roughening of the embossed sideto provide a secondary texture. Additional but otherwise identical filmsamples were roughened only on the embossed side with a greater degreeof secondary texture to provide average gloss readings on the embossedside of about 25. The gloss on the unmodified print side of thesesamples averaged about 19. Note that all gloss readings herein weretaken with the gloss meter (Byk Gardner micro-gloss 60°) parallel to theweb direction and are reported as an average of five readings for eachsample tested.

Top roller 38 rides on top of film 12 under a suitable pressure as film12 passes between middle roller 40 and top roller 38. In one embodiment,a top roller pressure of about 700 psi was found to be suitable. Thesurface of top roller 38 is desirably as smooth as is practicallyfeasible to help ensure that the top surface of film 12 in contact withtop roller 38 is correspondingly smooth for promoting print receptivecharacteristics. Optionally, the top roller 38 also has a resilient,rubber surface so that the risk of roller damage is minimized if the toproller 38 and the middle roller 40 were to come into contact. Aresilient rubber with a Durometer A hardness in the range of 60 to 80 at25° C. would be suitable. In one embodiment, top roller 38 has a rubbersleeve on a steel core. A rubber sleeve made from a silicon rubber havea 70 Durometer A hardness would be suitable.

The bottom roller 42 is positioned at the bottom of the 3-roll stack.The bottom roller 42 helps to avoid chatter and promotes a smoothrelease of film 12 from the texturing station 36. In one illustrativeembodiment, the bottom roller 42 has a smooth, chrome surface.

The path of film 12 through texturing station 36 is seen best in FIG. 2.The molten, extruded, molten film 12 extruded from the extruder 14 isintroduced to the texturing station 36 by feeding the molten film 12into the gap 45 between top roller 38 and middle roller 40. The toproller 38 applies pressure against the film 12, helping to hold itagainst middle roller 40. The smooth surface of top roller 38 also helpsto form a smooth, print receptive surface on the major face of the film12 adjacent to top roller 38. In the meantime, the middle roller 40contacts and texturizes the other major face of the film 12.

The three rollers 38, 40, and 42 are held at a temperature sufficientlybelow the melt temperature of the film material so that the film 12 setswhen the film material contacts these rollers. In one mode of practicefor processing a PVC film feed having a melt (exudate) temperature ofabout 380° F., the molten film 12 entering the texturing station 36 isat a temperature of about 350° F., the top roller is at 75° F., themiddle roller is at 185° F., and the bottom roller is at 175° F. The toproller 38 is cooler than the middle roller 40 so that the top surfacesets a little faster, which helps to promote formation of a smoother,print receptive surface on the face of the film 12 adjacent to the toproller. The middle roller 40 is warmer so that the film material sets alittle slower on the adjacent face, which helps the film material toconform to the texture of the middle roller 40 better than if the middleroller 40 were to be too cool. Heat exchanger 34 is coupled to texturingstation 36 in order to help control the temperatures of the rollers 38,40, and 42.

The speed of the film 12 through the texturing station 36 can vary overa wide range, such as from about 1 foot per minute up to about 1000 feetper minute or even more. Advantageously, a significant,printer-compatible texture can be formed on film 12 at high processingspeeds suitable for commercial scale manufacture. In one mode ofpractice, for example, roller speeds corresponding to a film speed ofabout 190 feet per minute at a tension setting of about 48 psi to about50 psi would be suitable.

The texture of the resultant film 12 may be characterized in terms ofthe Ra surface roughness of both the embossed and print sides of thefilm 12. In the practice of the present invention, Ra surface roughnessis the arithmetic mean deviation of the roughness profile, recordedwithin the evaluation length. Simply put, Ra is the average of a set ofindividual measurements of a surfaces peaks and valleys and is reportedin units of length, e.g., microinches (micrometers).

To measure the Ra surface roughness of the embossed side of the film,the film is placed print side down onto a piece of unscratched, unmarredglass. A perthometer instrument is placed on the film parallel to webpath. The device is activated and measurements are taken. The procedurefor measuring Ra surface roughness uses a Model M1 Mahr Perthometerinstrument commercially available from Willrich Precision InstrumentsCo., Inc. according to the procedure provided in the instrument'sinstruction manual titled “Operating Instructions 3755321; PerthometerM1 with PFM Drive Unit”, wherein the entirety of this instruction manualis incorporated herein by reference in its entirety. The unit is used inISO mode. The automatic function is not used. The maximum trace intervalof 0.7 inches is used. Five sampling lengths (cut offs) of 0.1 inchesare used, although seven such lengths are measured. The leading andtrailing measurements are discarded and the central five retained tohelp eliminate startup and stand-down noise. The NHT 6-100 stylus isused. The NHT 6-100 pick up is a single-skid pick-up whose skid has aspherical shape with a radius in the tracing direction of 25 mm and aradius at right angles to this of 2.9 mm and a contact point 0.8 mm infront of the stylus. The stylus tip has a radius of 2 micrometers and acone angle of 90 degrees per DIN EN ISO 3274. The measuring force isapproximately 0.7 mN. The tracing speed is 0.5 mm/s. The recordedprofile is filtered with a phase-corrected profile filter (Gaussianfilter) in accordance with DIN EN ISO 11562. Additional parametersettings for using the perthometer are as follows:

Language: English

Units: Inches

Timeout: On

Blocking: Off

V.24 38400 N 8120

Battery: 100%

Pick up type: 100

Corr. Value: 3%

N 5

PFM On

Lc Standard 320 ui

Autoprinting Off

Profile On

After taking the first measurement, the probe, or pick up, is moved afew inches away four more times with four more measurements taken ateach move. The readings are averaged, and the average is taken as the Rasurface roughness for that side of the film. To measure the Ra surfaceroughness of the printable side of the film, the film is turned andplaced on the same place on the glass. Measurements are done in theexact same way with readings averaged and recorded.

Desirably, the embossed side of the film has a deep surface texture, yetnot so deep that the film is incompatible with desired printingoperations. Thus, if the texture of the embossed side is too deep, thefilm could experience chatter, poor print quality or other trackingissues during printing. For this reason, the Ra surface roughness of theembossed side of preferred film embodiments is desirably at least 100microinches, preferably at least 120 microinches, and more preferably atleast 150 microinches. Desirably, the Ra surface roughness is no morethan 300 microinches, preferably no more than about 250 microinches; andthe ratio of the Ra surface roughness of the embossed side to theprinted side is in the range from about 1.2:1 to 500:1, preferably about3:2 to about 10:1; more preferably about 3:2 to about 3:1. Inillustrative embodiments of the invention, the embossed side of verypreferred embodiments of PVC films of the present invention had Rasurface roughness measurements in the range from about 160 to about 190microinches (averaging 168 microinches), while the printed sides ofthese films had Ra surface roughness values in the range from about 60to about 90 microinches, averaging 74 to 79 microinches. Consequently,in a particularly preferred embodiment, the Ra surface roughness of theembossed side is in the range of from about 160 microinches to about 190microinches, and the Ra surface roughness of the printed side is lessthan about 90 microinches, preferably less than 75 microinches, morepreferably less than 60 microinches, and in some desirable embodimentsis in the range of from about 60 microinches to about 90 microinches.

FIG. 3 is a copy of a pair of photographs showing the texture on thepre-embossed side 105 of the film and the print side 110 of the film100, respectively, taken at a magnification of 700%. The relatively deeptexture on the pre-embossed face 105 of the film 100 can be seen as arelatively random yet directional texture of protuberances projectingupward from the main face of this side of the film 100. The texture israndom in the sense that the features lack uniformity in two or more oflength, degree of meandering (deviation from linearity), height, andwidth, and general orientation. The texture is directional in that asubstantial portion of the protuberances generally have long axes thatgenerally run from the top to the bottom of the photograph, even thoughthe axes of features from top to bottom are not arranged in columns butinstead are irregularly staggered. Some of the features are branched,with multiple arms. The photograph of the print side 110 of the film 100shows a similar texture, but on a smaller scale.

Referring again to FIGS. 1 and 2 collectively, but mainly FIG. 1, thenext major station that the film passes through is the automatic profilecontroller station 46 which includes the profile controller 48, powersource 50, and electrical wiring 52 coupling power source 52 controller48. According to a feedback control loop, the controller 48 measures thethickness of the film 12 passing through controller 48. If the thicknessis outside of specifications, the controller 48 sends a signal to thedie heating source(s) causing the temperature at the die to increase orgo down. Generally, increasing the temperature at the die thins the film12, while lowering the temperature thickens the film 12. After theautomatic profile controller station 46, the edges of the film 12 aretrimmed at slitter 54. A pull roller 59 is positioned after slitter 54.Pull roller 59 is a driven roller that helps to pull the film 12 throughthe system 10. After slitting, the film 12 may then be transporteddirectly to a printing station (not shown), wound up and stored untilneeded, or otherwise handled. For purposes of illustration, FIG. 1 showsthat film 12 is wound and stored for further use on a take up roll 60 inwinder 56.

The thickness of film 12 can be selected within a considerably widerange. If too thin, however, the film 12 may have poor mechanical anddurability properties. Films that are too thick waste material and maybe more difficult to run through printing equipment, but thicker filmscertainly could be used where excess material usage is not a concern andprinting equipment is capable of handling the additional thickness.Generally, it is convenient to prepare embodiments of film 12 that havethicknesses in the range from about 1.0 mil or less to about 20 mils,preferably about 1.5 mils to about 2.5 mils.

Decorative information may be printed onto the film 12 to formdecorative laminate films, and these printed films may then beincorporated into decorative laminate structures using any suitabletechniques. Any kind of printed information may be printed directly ontothe print receptive side of film 12. The printed image may be, but isnot limited to an image of a wood grain, stone, marble, leather, fabricor other textile, porcelain, a metallic surface, a pattern, one or morecolors, a graphic image, combinations of these, and the like.Photographic images of people, animals, nature, places, things, and/orthe like also may be used. The decorative image may be a solid colorwithout a defined image. A variety of printing methods may be used toapply printed information onto the film 12, including by way of exampleink jet printing, laser printing, gravure printing, offset printing,anastatic printing, silk screen printing, transfer printing,combinations of these, and the like.

To accommodate the deep texture of film 12, it may be desirable toadjust print process parameters to obtain decorative film sheets whoseprinting satisfies desired quality and clarity standards. For instance,in the case of roto gravure printing, because of the rougher texture ofthe embossed side and of the moderate texture of even the printed sideof films in some embodiments, conventional settings useful may lead toimages that are too grainy and/or have dot skipping or print omits.Consequently, use of films 12 may require adjustments to parametersrelating to ink viscosity, nip pressure, line screen density on thedesign roll, and/or blade angles. Inks with moderately lower viscosityare desired in order to help insure that the thinner inks can adequatelyflow and cover the moderately textured printable film surface. Inrepresentative embodiments, suitable inks have a No. 2 Zahn viscosity atambient of about 18 seconds to 20 seconds.

Nip pressure is desirably increased moderately to help facilitate goodink penetration into the surface topography. Whereas conventional nippressures might be moderately below 40 psi, it is more desirable to usenip pressures above 40 psi. In one mode of practice, a nip pressure of45 psi is suitable.

The line screen density of the design roller can vary over a wide range.Often, a line screen density on the order of 150 lines per inch orhigher might be desired in a conventional printing operation. However,when printing onto a film surface with a moderate texture, using a linescreen density on the order of 150 lines per inch or less, desirablyeven 120 lines per inch, helps to pick up a greater volume of ink fromthe ink bath and leads to better coverage over the surface to beprinted.

The doctor blade angle is desirably reduced, too, in order to spread inkbetter in the current context. Blade angles ranging from 5 degrees to 25degrees with verticals ranging from 2⅝ inches to 4¼ inches have beensuitable. For instance, when printing a three color patterncorresponding to a wood grain texture, a blade angle of 25 degrees with2⅝ vertical is used to print a woodgrain tick; a blade angle of 15degrees and 2¾ vertical was used to print the woodgrain key, and a bladeangle of 5 degrees with a 4¼ inch vertical was used to print the solidbase color. Web tension of 8 to 15 psi would be suitable.

The resultant decorative sheet can be readily incorporated into a widevariety of decorative laminates. Examples from among many suitableapplications include flooring, worktops, wall coverings, desktops,furniture, electrical and appliance housings, cabinets and cabinet doors(kitchen, bathroom, bedroom, family room, living room, dining room,etc.), and the like.

In an exemplary decorative laminate construction, a decorative sheet isadhered to one or more substrates to form the desired end product or acomponent thereof. Any desired substrate may be used. The substrate canbe synthetic or natural. Examples include reinforced or unreinforcedpolymers, particleboard, medium density fiberboard, plywood, wood,paper, cardboard, metal, oriented strand board, wheatboard, strawboard,reconstituted cellulosic panels, polymeric foams, honeycomb structuralpanels, mineral filled polymer, concrete or other ceramic, or anunreinforced or reinforced polymeric layer, combinations of these andthe like.

In addition to the decorative sheet and the substrate, decorativelaminates of the present invention may include one or more additionallayers if desired. Examples include one or more additional decorativesheets in layers to create composite visual effects, overlays,underlays, adhesive layers as needed for laminating, and the like.Examples of such additional layers have been described in U.S. PatentPublication No. 2002/0168503, incorporated herein by reference in itsentirety for all purposes.

The laminates of the invention can be formed by any desired process.Typically, decorative laminates are formed by using adhesives andelevated temperatures and pressures to bond layers of the laminatetogether. Continuous laminating methods are preferred for commercialscale production. Suitable manufacturing lines should be capable ofrapid throughput with controlled temperature and pressure duringlaminating steps. Optionally, one or more layers of the product may beformed via coating a fluid composition, which may be a liquid,dispersion, or the like, which is then cured to form a solid or gelcomponent, as desired. Adhesives may be used to assist with bondingwhere needed. Hot melt, ultraviolet hardening, or heat hardeningadhesives are just a few examples of the many adhesives available in theindustry.

Decorative laminates, layers and features useful in decorativelaminates, methods of making these layers and features, and methods offorming the laminates are described in U.S. Pat. Nos. 6,436,540;4,816,314; 6,017,612; 4,076,566; 6,579,611; and 4,396,448; and in U.S.Pat. Pub. Nos. 2003/0116261; 2007/0087126; 2002/0168503; each of whichis incorporated herein by reference in its respective entirety for allpurposes.

Other embodiments of this invention will be apparent to those skilled inthe art upon consideration of this specification or from practice of theinvention disclosed herein. Various omissions, modifications, andchanges to the principles and embodiments described herein may be madeby one skilled in the art without departing from the true scope andspirit of the invention which is indicated by the following claims.

What is claimed is:
 1. A method of making a textured, decorative film,comprising the steps of: a) extruding a molten film, wherein the filmcomprises polyvinyl chloride; b) while the extruded film is at leastpartially molten, causing the film to pass through a gap between andcontact first and second tooling surfaces that are maintained at one ormore temperatures below the melt temperature of the molten film in amanner effective to help cause the molten film to set and solidify asthe film passes through the gap, said first tooling surface comprising aplurality of depressions on the first tooling surface that providecavities that are at least partially filled by the molten film as thefilm passes over the first tooling surface and sets, wherein saidplurality of depressions have a plurality of different shapes and aplurality of different dimensions, wherein said plurality of differentshapes comprise at least circular shaped depressions, and wherein saidplurality of depressions are randomly arranged on the first toolingsurface, and wherein said second tooling surface being relativelysmoother than the first tooling surface, whereby a solidified film isformed comprising a first, textured major face having an Ra surfaceroughness of greater than about 100 microinches and a second, printreceptive major face having an Ra surface roughness of less than 100microinches, wherein the ratio of the Ra surface roughness of the firstmajor face of the film to the Ra surface roughness of the second majorface of the film is in the range from about 1.1:1 to about 500:1; and c)printing decorative information onto the second major face of the film.2. The method of claim 1, wherein the film comprises less than 2 partsby weight of total plasticizer per 100 parts by weight of the film. 3.The method of claim 1, wherein the film comprises less than 0.1 parts byweight of total plasticizer per 100 parts by weight of the film.
 4. Themethod of claim 1, wherein at least a portion of the depressionscomprises generally flat bottoms.
 5. The method of claim 1, wherein thesecond tooling surface is biased toward the first tooling surface underpressure.
 6. The method of claim 1, wherein said plurality of differentshapes further comprise oblong shaped depressions.
 7. The method ofclaim 1, wherein the plurality of depressions cover at least 50% of thefirst tooling surface.
 8. The method of claim 1, wherein the first toolsurface includes a secondary texture formed at least on the depressions.9. The method of claim 1, wherein the depressions are formed over atleast 98% of the first tooling surface that contacts the film.
 10. Themethod of claim 1, wherein the first, textured major face has an Rasurface roughness of at least 120 microinches.
 11. The method of claim1, wherein the first, textured major face has an Ra surface roughness ofat least 150 microinches.
 12. The method of claim 1, wherein the firstmajor face has an Ra surface roughness of 160 to 190 microinches. 13.The method of claim 1, wherein the first, textured major face has an Rasurface roughness of 120 to 300 microinches.
 14. The method of claim 1,wherein the second, print receptive major face has an Ra surfaceroughness in the range from 60 microinches to 90 microinches.
 15. Themethod of claim 1, wherein the second, print receptive major face has anRa surface roughness of less than 60 microinches.
 16. The method ofclaim 1, wherein the ratio of the Ra surface roughness of the first,textured major face to the second, print receptive major face is in therange from about 3:2 to about 10:1.
 17. The method of claim 1, whereinthe ratio of the Ra surface roughness of the first, textured major faceto the second, print receptive major face is in the range from about 3:2to about 3:1.
 18. A method of making a decorative laminate, comprising;a) providing a decorative film prepared according to the method of claim1; b) directly or indirectly bonding the film to a substrate.
 19. Amethod of making a decorative film, comprising the steps of: a)extruding a film having first and second major surfaces, wherein thefilm comprises polyvinyl chloride, wherein a pattern of protuberances isformed on the first major surface while the film is at least partiallymolten, wherein said protuberances have a plurality of different shapesand a plurality of different dimensions, wherein said plurality ofdifferent shapes comprise at least circular shaped protuberances, andwherein said protuberances are randomly arranged on the first majorsurface; and b) after forming said pattern on the first major surface,printing decorative information onto the second major surface of thefilm.